Descaling cold water sprays under pressure of approximately 2000 psi commonly employed to remove oxides from metal strips during rolling in a hot rolling mill. In the prior art, various descaling nozzles are known for this purpose. The nozzles are commonly mounted on a water supply header above and across the metal strip for delivery of the well-defined high energy descaling sprays onto the strip. The prior art nozzles vary in their cost and complexity and also in their relative efficiencies.
It is the primary object of this invention to improve on the prior art nozzles for this purpose in a number of important respects.
More particularly, it is a prime object of the invention to provide a descaling nozzle of greater simplicity and easier installation which will deliver onto the metal strip a descaling spray of higher energy and better definition without turbulence. This objective is accomplished by providing a venturi-type nozzle entrance passage which quiets turbulence and increases water velocity through the nozzle tip.
Another objective is to eliminate the need for dirt screens and water diffusers at the inlet of the nozzle in order to prevent dirt clogging and reduced turbulence. This objective is accomplished primarily by burying or recessing the nozzle body deeply in the supply header so that dirt within the header will settle well below the nozzle inlet and will tend not to be drawn into the nozzle at start-up. Another benefit over the prior art achieved by the deep burying of the nozzle in the header is greatly reduced damage to projecting nozzle tips through collision with the hot steel strip or other impact.
Another important object of the invention is to provide more convenient, precise and economical spray alignment means whereby the several nozzle sprays on the header will overlap exactly without interference resulting in loss of spray energy. This objective is accomplished through a precise preset angle alignment for the nozzle tip relative to the nozzle body during assembly of the nozzle components, and the provision on the nozzle body of an indicator groove to permit precise alignment of each spray relative to other sprays and relative to the header when the nozzle bodies are threaded into the header.
Other features and advantages of the invention will become apparent during the course of the following description.